1. Field of the Invention
The present invention relates to a clamp structure for attaching a clip onto a flat cable in a reliable manner.
2. Description of the Related Art
Flat cables are used in an automobile to connect electric devices of the automobile to each other. The flat cable is generally furnished with clips. Each clip is attached to the flat cable using a clamp, thereby allowing the flat cable to be fixed in a prescribed position in the automobile body. In general, multiple clips are arranged along a flat cable in the longitudinal direction at a specific pitch. An example of these clips is disclosed in Japanese Patent Application Laid-Open No. 7-274357. This clip has a clamp structure comprising a bottom flange and a projection extending upward from the bottom flange. The projection is inserted between the adjacent wires that comprise the flat cable until the top portion projects from the top face of the flat cable. The projection is then heated and shaped into a top flange, whereby the top and bottom flanges hold the flat cable between them. However, if the flat cable consists of multiple layers of wires, the fused top flange can hold only the top layer of the flat cable, and the flat cable in contact with the bottom flange may shift.
To overcome this problem, a clamp structure 1 illustrated in FIGS. 1A and 1B has been proposed. The clamp 1 consists of a base 3 and a cover 5 pivoting about a hinge 25, and is capable of holding a flat cable 7 consisting of multiple layers of wires firmly.
The base 3 has a flat-cable receiving section 9 having a side-wall that receives a side edge of the flat cable 7. The cover 5 has a flexible pusher 23 in its inner face. The pusher 23 extends along the width of the flat cable 7, and hangs down from the inner face of the cover 5, and has a convex middle. When the cover 5 is closed, the pusher 23 comes into contact with the top face of the flat cable 7, and presses the top face of the multi-layered flat cable 7, while the pusher is deformed or flattened. Consequently, the flat cable 7 is held firmly between the pusher 23 and the base 3.
To prevent the clamp 1 from shifting greatly in a longitudinal direction along the flat cable 7, stoppers 29 are formed along the side edges of the flat cable 7 at predetermined positions, as illustrated in FIG. 2. This arrangement can maintain the clamp 1 in the designed position, while allowing for slight adjustment of the position of the clamp 1.
However, the pusher 23 of the conventional clamp 1 must have a large elasticity and flexibility to hold the flat cable 7 between the pusher 23 and the base 3. To this end, if the number of layers or the thickness of the flat cable 7 increases, the amount of deformation of the pusher 23 increases, requiring a large force to close the cover 5. This makes it difficult to attach the clamp 1 to the flat cable 7.
On the other hand, if the number of layers or the thickness of the flat cables 7 decreases, the deformation of the pusher 23 is slight, and the clamping force generated by the pusher 23 and the base 9 is weakened. This situation may cause the clamp 1 to shift along the flat cable 7.
In addition, many types of clamps 1 have to be prepared in accordance with different types or thicknesses of flat cables 7, and the conventional flat cable 7 itself needs to have stoppers or fringes 29 attached to it. For these reasons, the manufacturing cost of the clamp and the flat cable was high in the conventional art.
Therefore, it is one of the objectives of the invention to provide a clamp structure than allows the clip to be fixed to a flat cable in a reliable manner with a simple assembly process. The clamp structure improves workability, while reducing the manufacturing cost of the clip and the flat cable.
To achieve the objectives, a clamp that can hold a flat cable in a reliable manner under a small force is provided. The clamp comprises a base, a cover, a projection extending from the base toward the cover, and a pusher consisting of a pair of cantilevers positioned alternately. The base consists of a bottom and two sidewalls extending from the bottom and facing each other, and receives the flat cable. The cover is connected to one of the sidewalls of the base. When receiving the flat cable, the projection passes through the flat cable via a silt formed through or notched in the flat cable. The cantilevers hold down the flat cable when the cover is closed.
With this arrangement, the projection firmly rivets the flat cable, and at the same time, the cantilevers hold down the flat cable, thereby ensuring that the flat cable is held between the cover and the base in a reliable manner.
Preferably, the cantilevers are positioned at points symmetrical to the center of the cover so that the pushing force is applied to the flat cable uniformly. The cantilevers are made of an elastic and flexible material whose restoration force holds down the flat cable when the cover is closed.
Each cantilever has a guide face that slides along the surface of the flat cable, or along the side edge of the flat cable if the flat cable is multi-layered, as the cover is closed, allowing the cover to be closed smoothly.
The clamp also has a clip extending from the reverse side of the bottom of the base, in a direction opposite to the projection. The clip allows the flat cable to be attached to, for example, an automobile body.
Preferably, a lock protrusion is formed on the outer face of the other sidewall, and a lock arm is formed in the end of the cover, so that when the cover is closed, the lock protrusion engages with the lock arm. The lock protrusion and the lock arm can securely hold the cover around the flat cable.
In another aspect of the invention, a clamping structure comprising a flat cable and a clamp attached to the flat cable is provided. This clamp structure simplifies assembling steps for fixing the flat cable to, for example, an automobile body. The flat cable consisting of a multiple conductors arranged in parallel to each other at a predetermined interval and an insulator covering and coupling the conductors. The flat cable has a slit in the insulator between adjacent conductors. The clamp has a U-shaped base for receiving the flat cable, a cover connected to the base, a projection extending from the base, and a pusher formed in the cover and holding down the flat cable when the cover is closed. The projection is fit into the slit of the flat cable. The slit is formed through the insulator, or alternatively, it is notched in the insulator with a thin portion left. In the latter, the projection of the clamp penetrates the thin portion when it is fit into the slit. The pusher consists of a pair of cantilevers positioned alternately so as to securely hold down the flat cable without requiring much force when the cover is closed.